Marking device for navigating instruments



April 28, 1942. R PA E 2,280,844

MARKING DEVICE FOR NAVIGATING INSTRUMENTS Filed Feb. 24, 1941 2 23w 4]ll 1| 22 22+ f3 :1 1 057 12 IllIHIIIIIIIIIIIIHHHI 22 IIIIII PatentedApr. 28, 1942 MARKING DEVICE FOR -NAVIGATIN G IN STBUMENTS RobertHumphrey Page, Montreal, Quebec, Canada, auignor to Bendix AviationCorporation, Bendix, N. 1., a corporation of Delaware ApplicationFebruary 24, 1941, Serial No. 380,190

4 Claims.

This invention relates to navigating instru- 'ments and particularly tothose of the type of sextants and octants.

It is specially adapted for attachment to the instrument patented in theUnited States under No. 1,970,543 dated August 21, 1934.

Its object is to provide simple and rapid means for graphicallyrecording a series of observations whereby an average reading may beobtained.

These observations are recorded without changing the grip of theinstrument and byv a slight sideways movement of the thumb.

They are marked on the instrument on the surface of the knurled thumbcylinder by a pencil on the end of a bell crank lever pivoted on theside of the instrument, adapted to make a vertical mark when actuated bya slight sideways pressure of the thumb. When a series of observationshave been so marked, a central point is noted and marked and broughtunder the pen 011 point, and a reading of the scale is made.

"This simple and rapid method replaces the present cumbersome and slowmethod of copying down the reading of each observation and thencalculating the average of them.

This latter method required the grip of the hand to be released aftereach observation and the writing down the figures of each reading.

In the piloting of aeroplanes the element of time may be very importantin making observations and rapidity of action is most desirable owing tovariable conditions such as clouds.

In describing the device reference is made to the accompanying drawingin which:

Figure l is a side view of an octant with the device mounted thereon andin normal position.

Figure 2 shows an end view of the device apart from the octant.

Figure 3 shows 'a knurled cylinder with a series of markings thereon;

Figure 4 shows the operation of the device.

In Figure 1 is shown a side view of the instrument described in UnitedStates Patent No. 1,970,543 and illustrated in Figure 2, of that patent.

The only change in the construction required besides the addition of amarker and actuating means therefor is'that the thumb wheel 2 has theknurling narrowed to provide a cylindrical.

smooth surface 2| between the scale 22 and the knurling 20.

This surface 2| should be suitably treatedand prepared to receive pencilmarks which are clear- 1y visible and ca be readily removed or erased.

A 'process known as fanodizing may be used to treat the surface 2| inorder to render it smooth so that visible pencil marks may be madethereon, said process being a. process similar to electric-plating andused to render aluminum surfaces non-corrosive. The process, which iswell known, is carried out by immersing the aluminum parts in anelectrolytic solution of chromic acid or sulphuric acid with the partsconnected to the anode of the electroplating apparatus, and passing anelectric current through the electrolyte, whereby nascent oxygen isliberated at the anode and combines with the aluminum to form a smoothsurface of aluminum oxide on the aluminum partsbeing treated, aluminumoxide being more resistant to corrosion and forming a smoother surfacethan aluminum itself.

Mounted on the side I!) of the lower front portion of the instrument, isa pivot pin 3 on which is pivoted a bell crank lever, having legs 4 and5. The leg 4 is hollowed to receive a pencil bearing tube 40 and aspring 4| to permit the tube 40 to retire into the leg 4 when the pencilpoint 42 is pressed againstthesurface 2|.

The leg 5 extends to its end 50 which normally meets astop l2'on thewall ll of the instrument I. A spring 6 mounted on a screw bearsupwardly on the leg 5 to hold the end 50 on the stop I 2 and at the sametime hold the pencil point 42 free from contact with the surface 2|.

Projecting outwardly from the leg 5 is a vertical plate 5|, whichprovides the means of operating the bell crank lever. and causing thepencil point 42 to produce a vertical marking on the surface 2|.

A stop pin 1 limits the action of the leg 5 and prevents the pencilpoint 42 reaching the scale 22 in its descent.

When the observer has adjusted the instrument to a star by his thumbrotating the thumb wheel 2 he then moves the side of his thumb outwardsand presses the plate 5|. This operates the lever and causes the pencilto mark the surface 2| with a vertical marking. By repeating observer isthereby able to complete his observation in a very short period of time.

The devicecan be readily applied to instruments in use with very slightalterations to them.

The detail construction of the device may be changed without afiectingthe scope of the invention.

What I claim is:

1. In combination, a navigating instrument of the class described havinga thumb wheel the peripheral portion of which is provided with a markingsurface, means for marking said surface, and operating means for saidmarking means extending within reach of the thumb of the hand holdingand adjusting said instrument.

2. In combination, a navigating instrument of the class described havinga thumb wheel the peripheral portion of which is provided with a markingsurface, marking means including a bell crank lever pivoted to the sideof said instrument and having a stylus adapted to mark said surface, andoperating means for said marking means extending within reach of thethumb of the hand holding and adjusting said instrument. e

3. In combination, a navigating instrument of the class described havinga thumb wheel the.

peripheral portion of which is provided with a marking surface, markingmeans including a bell crank lever pivoted to the side of saidinstrument and having a spring mounted pencil point on one leg formarking said surface, means extending outwardly from the other leg ofsaid bell crank within reach of and adapted to be operated by the thumbof the hand adjusting said thumb wheel, said other leg having a springtending to i normally hold said pencil point away from said *markingsurface, and a stop to limit the stroke of said pencil point.

A RQBIR'r HUMPHREY PAGE.

